CALB2 and Alzheimer disease: Calretinin is a calcium-binding protein parvalbumin (PV), and cells expressing this protein are also reported to be either preserved, increased, or decreased, depending on the cortical region reported in various models of AD from early to late stages of the disease (Yang et al. 2018; Zallo et al. 2018; Petrache et al. 2019) which could be associated with calcium homeostasis.